Why do i have problems with 4x250


Premium Member
Since i change from 2x400w to 4x250w (both set up run reeflux 10k) I have lots of problem with corals getting burn. According to Sanjay's lighting 400w HQI ballast with reeflux 10k has 170 PPFD and 113 PPFD on the 250w HQI.

My parameter as follow:

Ca 420
Mg 1300
Kh 8.0
NO3 0ppm
PO4 0.02 PPm (Hanna)
Temp 78-80F
Ph 8.0-8.16

Any idea? BTW, i did not acclimate my corals with the new lighting. Is that the cause? Please help... Thanks


In Memoriam
thats about 100 ppfd difference. and not acclimating that difference can be stressful.

also, if you have 2 x 400 covering the same tank as the 250's, the intensity would be lower on the 400's due to the spread. you would have 2 hot spots with big gaps between the 2 bulbs with lower intensity. With 2 bulbs, you have 4 hot spots, with less gap between the bulbs.



Premium Member
That is what i thought :)... Well all my tort already got burn and slowly recover. Hopefully, everything will get back to normal soon.

How high do you hang your pendant from the water surface?


Active member
I use 250w reeflux in e-ballasts. I have them 8" off the water and have lowered my photo period to 4 hourd because some corals were getting bleached. When they recover I might slowly increase the photo period.


Premium Member
Thanks Prodman.... I have mine running 8hrs a day now and the pendant approx 6" from the surface. I think it is too low.